Give two examples each of (i) group 2 elements and (ii) group 18 elements.

(a) What is meant by (i) a group and (ii) a period in a periodic table? (b) How many periods and groups are there in the long form periodic table? (c) Give two examples each of (i) group 1 elements (ii) group 17 elements (iii) group 18 elements.

Group 2 elements are

Group 2 elements belong to

The valency of group 16 elements 2 .

Devendra was told that the elements P,Q and R belong to group 2 , group 14 and group 17, respectivelhy, of the long form of periodic table. Based on this information, he was asked to answer the following questions: (a) What is the valency of (i) element P (ii) element Q and (iii) element R ? Give reasons for your answer. (b) What is nature of oxide of (i) element P (ii) element Q and (iii) element R ? Give reasons for your answer. (c) Give one example each of (i) element P (ii) element Q and (iii) element R . (d) Name three elements which occur in the same group as element R but exist in three different physical states at room temperature. (e) What values are displayed by Devendra in answering these question?

The elements of group 18 are called

The group 18 element placed in period 3

Based on the group valenvy of elements write the molecular formula of the following compounds giving justification for each: (i) Oxide of first group elements. (ii) Halide of the elements of group thirteen, and Compounds formed when an element, A of group 2 combines with an element, B of group seventeen.